CONCORD, N.H. (AP) - Hospitals across the country recommended hepatitis C testing for about 7,900 patients last summer after a traveling medical worker was accused of stealing drugs and infecting patients with tainted syringes in New Hampshire. But five months later, nearly half of those who were possibly exposed to the liver-destroying disease in other states have yet to be tested.

Described by prosecutors as a “serial infector,” David Kwiatkowski is accused of stealing syringes of the powerful painkiller fentanyl from the cardiac catheterization lab at New Hampshire’s Exeter Hospital and replacing them with saline-filled syringes tainted with his own blood. In jail since his arrest in July, he pleaded not guilty to 14 federal drug charges earlier this month and is expected to go to trial next fall.

Before April 2001, when he was hired in New Hampshire, Kwiatkowski worked as a traveling cardiac technologist in 18 hospitals in seven states, moving from job to job _ despite being fired twice over allegations of drug use and theft.

Thirty-two people in New Hampshire have been diagnosed with the same strain of hepatitis C that Kwiatkowski carries, along with six in Kansas, five in Maryland and one in Pennsylvania. At least 3,700 people outside New Hampshire have yet to be tested, hospitals and public health officials told The Associated Press.

For example, in Michigan, where Kwiatkowski grew up and started his career, about 2,300 patients at five hospitals were notified that they may have been exposed to hepatitis C by Kwiatkowski. As of early December, only about 500 had gone in for testing, none of whom were diagnosed with a strain linked to the New Hampshire outbreak, according to the Michigan Department of Community Health.

In Pennsylvania, 2,280 patients at the University of Pittsburgh Medical Center Presbyterian were notified that they should get tested, but only 840 have, one of whom was diagnosed with a matching strain of hepatitis C.

Kwiatkowski was fired a few weeks into his temporary job at UPMC in 2008 after a co-worker accused him of swiping a fentanyl syringe from an operating room and sticking it down his pants. Citing a lack of evidence, hospital authorities didn’t call police, and neither the hospital nor the medical staffing agency that placed him in the job informed the national accreditation organization for radiological technicians. Within days, Kwiatkowski was starting a new job at the Baltimore VA Medical Center, where one patient also has since been diagnosed with hepatitis C linked to Kwiatkowski.

Though the VA center initially said it had identified 168 patients who may have been exposed, that number was later lowered, and 68 patients ultimately were tested. Two other Maryland hospitals where Kwiatkowski worked also have completed their testing, with no diagnosed cases of hepatitis C matching Kwiatkowski. But at the fourth, The Johns Hopkins Hospital in Baltimore, four patients have been diagnosed with the strain of disease linked to Kwiatkowski.

About 500 of the 1,567 patients notified by Johns Hopkins have yet to be tested, according to hospital spokeswoman Kim Hoppe. Kwiatkowski had been referred by a staffing agency that assured Johns Hopkins that it had followed a vigorous vetting process, Hoppe said. He worked there for two 13-week stints, from July 2009 to January 2010.

Saint Francis Hospital in Poughkeepsie, N.Y., where Kwiatkowski worked in late 2007 and early 2008, notified and tested 31 patients without finding any linked cases to Kwiatkowski. In Kansas, nearly all of the 416 patients who may have been exposed at Hays Medical Center have been tested and six have been diagnosed with infections linked to the New Hampshire outbreak.

There have been no cases linked to Kwiatkowski in Arizona, where about 300 patients from two hospitals have been asked to get tested and about 280 have done so. Kwiatkowski worked at Maryvale Hospital in Phoenix in 2009 and the Arizona Heart Hospital in 2010. He was fired from the latter job after 10 days after a co-worker found him passed out in a bathroom stall with a stolen fentanyl syringe floating in the toilet.

That incident was reported to police, Kwiatkowski’s staffing agency, a state regulatory board and the national accreditation organization, but the accreditation group dropped its inquiry after learning police hadn’t filed charges.

Days later, Kwiatkowski landed a new job filling in for striking technicians at Temple University Hospital in Philadelphia. That hospital has recommended testing for 312 patients but won’t say how many have followed through or have been diagnosed with hepatitis C. A hospital spokesman referred questions to the city health department, which did not return calls.

Testing also is still under way in the last place Kwiatkowski worked before heading to New Hampshire _ Houston Medical Center in Warner Robins, Ga. According to the hospital, fewer than 100 people have yet to be tested, and there haven’t been any cases yet linked to Kwiatkowski.

In New Hampshire, where about 3,300 patients were tested, Kwiatkowski is charged with seven counts of illegally obtaining drugs and seven counts of tampering with a consumer product, though prosecutors have said further charges are possible. Although New Hampshire cannot charge him for possible violations in other states, it can use evidence gathered in those jurisdictions in its trial, U.S. Attorney John Kacavas said. Other states are waiting to see the outcome of New Hampshire’s case before deciding whether to file charges, he said.

“We continue to reach out to other states affected by this matter,” Kacavas said this week. “Other health organizations and departments continue to do their work in their states, but nothing has changed in the sense that our prosecution will go forward. At this point, we are the only prosecution in the country, and we’ll see how it rolls out.”